Preferred Sassafras habitat. |
In the
Orinoco River basin of Colombia there are several endangered tree species. One
of them is the Sassafras or Ocotea
cymbarum, a member of the Lauraceae family. It is listed in the IUCN’s Red
List of vulnerable and endangered species. Its North American cousin was almost
harvested to extinction, in order to make root beer, a beverage that was
popular in the 19th and 20th centuries, and which is sold
today as a type of soda pop, but thankfully without any Sassafras-based
contents.
Ecologists meet a Sassafras |
The South
American Sassafras has experienced similar uncontrolled extraction, primarily
for its aromatic wood used in fine carpentry, but also in order to produce safrole
oil for biofuel. In the 1960’s the use of safrole oil for human consumption was
banned by the U.S. Food and Drug Administration, as studies suggested it is
carcinogenic, with more bans that followed by European and other authorities.
However, this did not stop the harvesting of Sassafras trees for carpentry
uses.
Looking for Sassafras trees. |
Ocotea cymbarum grows in the gallery forests and inundation
forests of the Orinoco River basin. Its preferences make it a difficult species
to work with. For starters, it prefers a lot of shade, which means that it
cannot be cultivated in open settings. At the Reserva Natural La Pedregoza in Vichada, Colombia, planting
experience shows that only those seedlings planted inside the rain forest
survive, and that any attempts to establish the tree in non-shaded areas are a
failure. This greatly limits the possible sites for restoration activities with
this tree.
Obtaining
seeds from Sassafras trees is also a challenge. There are male and female
trees, and only the female trees have seeds. Due to past harvesting, this has
caused further pressure on the species. For
example, when the natural reserve at La Pedregoza was established, only 4
mature Sassafras trees were found, 3 of which were males and 1 a female some 3
kilometers away from the males, making pollination extremely problematic. This
low surviving density, more than anything else, encouraged the tree planters at
La Pedregoza to make every effort to restore the tree to a self-propagating
density inside the natural reserve.
The seeds
ripen in May and June, which coincides with the beginning of the wet season and
the inundations. Since the trees have large, branchless and straight trunks and
can grow to be over 25 meters in height, climbing the trees to collect the
seeds is very dangerous. To add to the problem, the seeds are a favourite food
for several types of fauna, especially macaws and parrots. This means that tree
planters and birds are often in conflict when it is time to collect the seeds.
Much relies on finding a compromise between the birds’ dinner plans and the
needs of the tree planters when seed collecting time rolls around.
Good quality Sassafras seeds. |
The seeds
are quite large and very humid inside. This too causes a challenge, as only
natural fiber cloth bags can be used to collect the seeds; otherwise they rot
in the tropical heat. For that reason plastic bags are a complete no-no. For
best germination results in the tree nursery, seeds should be no more than 1
week old from the time they are collected to the time that germination is
attempted in the tree nursery. La Pedregoza has employed indigenous people to
collect the seeds, a practice which has required considerable logistical
support to get the seeds to the tree nursery in a timely manner.
There are
only some 80 to 90 Ocotea cymbarum
seeds in a kilogram (40 seeds per lbs.). Due to the many challenges already described
the average cost of collecting a kilogram of Sassafras seeds works out to be about
$100 USD, with no guarantee of germination. In addition, the manner in which
the tree’s roots develop, means that larger planting bags are required in the
tree nursery, each using a lot more substrate in order to fill each bag. The
subsequent transport of the bags to a planting location is complicated due to
the added weight caused by having large planting bags. Someone has to physically
carry those bags into the rain forest, as vehicle access is not possible.
Planting Sassafras in shaded spots. |
At
La Pedregoza the average germination rate for Sassafras has been around 80%
with good seeds. The seedlings need about 4 months in the tree nursery, before
they reach a viable size for transplanting in the forest. We use a 60% shading
material while the seedlings are in the nursery, as they are quite sensitive to
full sunlight even in their initial development. Since the seeds are collected
quite late in the season, planting can´t really occur until October at the
earliest, once flood waters start to recede from the inundation forest. La
Pedregoza teams have planted Sassafras as late as December, when the final
flood waters disappear.
Transplanting
offers a further challenge, as any miscalculation in the selected planting site
can result in a failure. Some natural predators seem to like to graze on the
seedlings as well. In the past 3 years La Pedregoza has planted over 1,000
Sassafras trees in the rain forest, with only a 50% survival rate after one
year. Working with Ocotea cymbarum is
a labour of love, but considered by everyone to be well worth the effort, from
seed collectors to tree nursery staff to the final tree planters, as well as
the biologists and botanists supervising the process. The support of Tree-Nation members has been fundamental in this work, so everyone involved can
truly state that they have helped save an endangered species.
Copyright (c) 2017 Corporacion Ambiental La Pedregoza